Re: [RFC v2 1/4] mm: make alloc_pages_exact_node pass __GFP_THISNODE

From: David Rientjes <rientjes@google.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>, Greg Thelen <gthelen@google.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Subject: Re: [RFC v2 1/4] mm: make alloc_pages_exact_node pass __GFP_THISNODE
Date: Fri, 24 Jul 2015 16:09:05 -0700 (PDT)	[thread overview]
Message-ID: <alpine.DEB.2.10.1507241606270.12744@chino.kir.corp.google.com> (raw)
In-Reply-To: <55B2A596.1010101@suse.cz>

On Fri, 24 Jul 2015, Vlastimil Babka wrote:

> > I assume you looked at the collapse_huge_page() case and decided that it 
> > needs no modification since the gfp mask is used later for other calls?
> 
> Yeah. Not that the memcg charge parts would seem to care about __GFP_THISNODE,
> though.
> 

Hmm, not sure that memcg would ever care about __GFP_THISNODE.  I wonder 
if it make more sense to remove setting __GFP_THISNODE in 
collapse_huge_page()?  khugepaged_alloc_page() seems fine with the new 
alloc_pages_exact_node() semantics.

> >> diff --git a/mm/migrate.c b/mm/migrate.c
> >> index f53838f..d139222 100644
> >> --- a/mm/migrate.c
> >> +++ b/mm/migrate.c
> >> @@ -1554,10 +1554,8 @@ static struct page *alloc_misplaced_dst_page(struct page *page,
> >>  	struct page *newpage;
> >>  
> >>  	newpage = alloc_pages_exact_node(nid,
> >> -					 (GFP_HIGHUSER_MOVABLE |
> >> -					  __GFP_THISNODE | __GFP_NOMEMALLOC |
> >> -					  __GFP_NORETRY | __GFP_NOWARN) &
> >> -					 ~GFP_IOFS, 0);
> >> +				(GFP_HIGHUSER_MOVABLE | __GFP_NOMEMALLOC |
> >> +				 __GFP_NORETRY | __GFP_NOWARN) & ~GFP_IOFS, 0);
> >>  
> >>  	return newpage;
> >>  }
> > [snip]
> > 
> > What about the alloc_pages_exact_node() in new_page_node()?
> 
> Oops, seems I missed that one. So the API seems ok otherwise?
> 

Yup!  And I believe that this patch doesn't cause any regression after the 
new_page_node() issue is fixed.